Combined experimental and theoretical studies on a series of mononuclear Ln single-molecule magnets: dramatic influence of remote substitution on the magnetic dynamics in Dy analogues
A series of Ln III complexes of general formula [Ln(H 2 L 1 ) 2 (NO 3 ) 2 (H 2 O)](NO 3 ) ( 1-5 ) [Ln = Dy ( 1 ), Tb ( 2 ) Ho ( 3 ), Er ( 4 ), and Yb ( 5 )] and an analogous Dy III complex with ligand H 2 L 2 , [Dy(H 2 L 2 ) 2 (NO 3 ) 3 (H 2 O)](NO 3 ) ( 6 ), where H 2 L 1 and H 2 L 2 stand for ( E...
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| Published in | Dalton transactions : an international journal of inorganic chemistry Vol. 52; no. 5; pp. 1241 - 1256 |
|---|---|
| Main Authors | , , , , , |
| Format | Journal Article |
| Published |
31.01.2023
|
| Online Access | Get full text |
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| Summary: | A series of Ln
III
complexes of general formula [Ln(H
2
L
1
)
2
(NO
3
)
2
(H
2
O)](NO
3
) (
1-5
) [Ln = Dy (
1
), Tb (
2
) Ho (
3
), Er (
4
), and Yb (
5
)] and an analogous Dy
III
complex with ligand H
2
L
2
, [Dy(H
2
L
2
)
2
(NO
3
)
3
(H
2
O)](NO
3
) (
6
), where H
2
L
1
and H
2
L
2
stand for (
E
)-2-[(2-hydroxyphenyl)iminomethyl]-6-methoxy-4-methylphenol and (
E
)-2-[(2-hydroxy-5-methylphenyl)iminomethyl]-6-methoxy-4-methylphenol, respectively, have been synthesized and magneto-structurally characterized. All these complexes are isostructural and isomorphous, in which the zwitterionic form of the ligands predominantly coordinate the metal centers. The magnetic study revealed that complex
3
displays negligible SMM behaviour, while
1
and
6
are zero field SMMs, the performance of which can largely be improved in the presence of an applied dc field by lowering under barrier relaxation processes, and finally
2
,
4
, and
5
are field-induced SMMs. The most remarkable observation in the present study is the dramatically-enhanced SMM performance in
6
compared to
1
, achieved by only a remote methyl substitution at the ligand framework to increase the intermolecular separation. Although SINGLE_ANISO
ab initio
calculations for
1
and
6
are very similar, the POLY_ANISO module revealed weak dipolar interactions in both the compounds but significant antiferromagnetic interaction in
1
, thereby justifying the experimental fact. The present work discloses that even a small substitution such as a methyl group can adequately increase the intermolecular separation, leading to several-fold enhanced effective energy barrier.
A series of mononuclear Ln
III
single-molecule magnets reveals a dramatic influence of remote substitution on magnetic dynamics in Dy analogues. |
|---|---|
| Bibliography: | 2213351-2213356 For ESI and crystallographic data in CIF or other electronic format see DOI https://doi.org/10.1039/d2dt03354b 1-6 for complexes Electronic supplementary information (ESI) available: Fig. S1-S28 and Tables S1-S11. CCDC |
| ISSN: | 1477-9226 1477-9234 |
| DOI: | 10.1039/d2dt03354b |